Hi Hambers! I'm very curious how much would be my quarter mile time but I haven't been at a dragstrip yet. My car is a chopped A sedan with a Ford 390, cammed(exrreme energy 270), streetmaster intake, 600 Holley, electronic ignition. Do you know what have I expect of that car? What is your times with Model A's? The car is in the break in period, it has only about 150 miles in the engine, it's totally rebuilt. Thanks!
Quite a bit would depend on rear end ratio and transmission as well. A high-stall automatic will beat an identical manual shifted car any time, unless you're Ronnie Sox. For 1/4 mile racing, you want to have a rear end ratio that let's your engine reach peak horsepower RPM just as you blow through the traps.
You cant really know till you take it to the track. Alot depends on your traction. You can have 900 horses but if you cant hook it up than you aint fast. Ive got 450hp but the last time i ran my car best i could do was low 15's in the quarter. At the time i had no posi, gears were 2.72, and stock good year tires that spun most of the way thru the 60ft mark unless i eased into the throttle. My suggestion is to drive around about a week change the fluid and then go race it.
May it could help: 2.41 rear gears and posi traction. I have a 5 speed truck ****** with about 3.9 first gear ratio. That's why I left the low rear ratio. I thought maybe they can equalize each other. The car is around 1800 lbs. Rear tires are 27" diameter.
do the tires stick? My et changes a second and a half by changing from normal street radials to drag radials
Usually normal street tires will work ok to low 14s or high 13s, but if the car is quicker they won't hook and you'll still only go mid-high 13s.
To me his choice of ******, tire hieght and rear gear ratio is all wrong. Someone with a slide rule will figure it out shortly but real world times take trile and error. JMO
I don't know anything about the trans you are useing and your 2:41 rear ratio is not low but very high............... The only thing you have going for yourself is a torqy motor and a light wieght car. Like already said, you can have all the power in the world but if it dosn't stick you go know where!
You cant make it better till you try racing it to get a base run. If you get into a low 13's or better yet 12's feel proud. Thats great for a street car. Once you dip into the 11's you gotta run a roll cage.
I am just curious because I haven't raced a car like this before. I think it's about 300 hp and very low weight. Can't wait to try it!
High geared cars with pickup transmissions aren't exactly the hot set up to race, but with a relatively light car with a pretty big engine, you might do better than most expect. Like everyone says, go run the car, get a baseline and start figuring out how to make it quicker. And I'm kind of curious, can you even use overdrive (I ***ume the 5 speed is overdrive, but I don't know for sure) with 2.41's on the street? Most performance overdrive setups I see usually have somewhere between 3.42 and 4.11 gears in them. Larry T
M5R2 gear ratios: 3.75, 2.32, 1.43, 1.00, 0.75. My second gear seems like a first gear in an automatic ******. Therefore I left the 2.41 gears. I will try what happens in a race and maybe I will go higher. But I don't wanted to just spin the tires in first gear because of the high first gear and high rear end ratio.
Larry, I used the 5th gear yet. It was very fun to cruise in a high speed nearly at idle. The car is low weight therefore the engine had enough torque to move the car.
CoolCat82, Your transmission gear ratios aren't as bad as I figured they would be (think grannygeared early pickup 4 speeds). Take it and run it, it should be fun!! As far as spinning the tires more with low gears, I don't think it's that bad of a problem. If you break the tires loose in a high geared car, the tire is spinning faster than it would be in a low geared car. It seems like it's harder to recover and get it to hook up than it is with low gears. Take that for what it's worth, just my opinion. I did some quick calculations on your gear ratio. It looks like around 1500rpms/70mph for your 2.41s. If you dropped back to around 3.50 gear ration, you'd be running around 2200rpms/70mph. That's still in the low side of the cruising comfort range. Just something else to consider if you decide you wanna improve your time slips. Larry T
Hey, there's a formula that kinda goes bore x stroke x rpm x rear gear ratio divided by rear tire cir***ference.....yada, yada, yada. Dig around and you'll find it. I got it wrote down in my cheaters notebook at my shop. It gives you a general idea of how to set a car up. First you gotta know how fast you wanna go and a rough idea of horsepower...... Well, on 1/4 mile times, alot of things come into play. I deal with Alky/FC's and top fuelers. Let me just say this, this one person was putting out well over 4000 HP, normally runs high 4.0's, maybe low 5's. Stages, lites pop, makes it about 20 feet, tires break loose, goes up in smoke, gets out of it, lets the rpm drop some, gets back into it, goes bout 100 or so feet, goes back to smokin agian, lets out of it........runs about 165mph at about 8.5 seconds. These numbers are really strange.....if you didn't see the race and just heard the numbers back in the pits, you'd go, ' What tha Heck..........' Guessing really doesn't cut it, but when high horse numbers are involved even in street cars, you can get some really strange stuff that doesn't quite jive. I saw this Diesel race truck, had 2 or 3 turbos on it, it was running its *** off, either blew its engine or lost something critical, coasted thru the lights at 100 mph with about a 11 second et. M*** and energy can do some amazing stuff, not to mention wind drag............. Best thing to do is take it out to the track after you engine has been broke in, taking you time, making about 4 or 5 p***es. Usually every drag strip has a few days it opens to let the guys get their setups dailed in, they don't mind the rod guys come on in and do their thing...........Hope this helps
Screamin' Metal is right, there are all kinds of calculators and formula's for figuring this stuff out. I believe Isky was one of the first to bring out a calculator called a "Dream Wheel" back in the 60's. Moroso still sells a Power/Speed calculator, I think. They both work like a slide rule, dial in the horsepower/weight and it spits out an et/mph and some other calculations like gear ratio/tire size/rpm.. Of course it's a perfect setup kind of deal and you're not gonna run exactly what it says, but it gets you in the ballpark. Here's a couple of helpful websites I use once in a while. I told someone the other day that if I knew what I know now when I was in school, I'd have paid more attention in math cl***. There's a reason that a lot of the top dragracers have Engineering Degrees. http://www.race-cars.net/calculators/et_calculator.html http://www.bgsoflex.com/auto.html
There's a lot of little tricks you can do to also fine tune you rod also, you can play with timing, carb jetting, even play with home made restrictors in your collectors. But the main thing, get a couple of sets of old rims that are in good shape......you can tune with tire sizes and this acn make a big difference on a small budget. Just measure you dia. go a little bigger, make a few runs, then go a little smaller, get a feel for what the car likes. These old rods have likes and dislikes.....they'll run better one way and not the other. They all have personalities!
Brake the dam thing in at the drag strip. When was the last time that you heard a top fuel driver say " I have to brake in my engine" ???? It will ether go or you will be charged with a OIL DOWN. See ya at US30
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